1. Field of the Disclosure
The present disclosure relates generally to a drive mechanism for a fuser assembly in an imaging device, and particularly to a drive mechanism for a fuser backup member that allows for an amount of reversing of the drive gear for opening the fusing nip of the fuser assembly without reversing the rotation of the backup member.
2. Description of the Related Art
To simplify the design reduce cost, some fuser assemblies for electrophotographic imaging devices, such as laser printers or copiers, utilize only one motor for operating the fuser assembly. For a single motor fuser, the motor has two functions. One function is to run or operate the fuser in the process direction during printing to effectuate toner fusing, by driving the backup roll and exit rolls in the fuser. A second function is to open and close the fusing nip and exit nip. Fuser nip opening and closing may be achieved by turning the motor in the reverse process direction, relative to the rotational direction for moving sheets of media during a fusing operation. In earlier belt-based fuser designs with the backup roll gear fixed to the backup roll shaft, when the fuser was driven in the reverse direction to open or close the nip, the backup roll would also rotate and rub against the fuser belt. This rubbing in the reverse direction was not desirable since debris on the surface of the backup roll was seen to scratch the surface of the belt and backup roll when they are not turning together.
Some prior designs included a one-way clutch introduced between the backup roll drive gear and the backup roll shaft. When driving the drive gear in the process direction, the one-way clutch would engage the backup roll shaft and turn the backup roll. When driving in the reverse direction, the one-way clutch releases and allows the drive gear to turn freely on the backup roll shaft. Despite the successful operation of this design, a disadvantage is that it is relatively expensive and increases the overall price of the fuser.